Cult leader David Koresh and 75 of his Davidian followers died in a hellish, CS-fuelled inferno 20 years ago today after a 51-day siege of their compound by the FBI and ATF in Waco, Texas. The fallout of the siege, including subcommittee hearings and criminal trials, revealed the grim psychology of the government agencies and questioned deeply the way America treats groups on the fringe of society.

The background story is long, sufficiently wacky by cult standards, and not altogether relevant. For our purposes the story begins with the Bureau of Alcohol, Tobacco and Firearms fibbing about the Branch Davidians' stockpile of gun parts in order to get a warrant to raid their compound.

At the time, David Koresh, who saw himself as the last prophet, led an off-shoot sect of the Seventh Day Adventist Church concerned with the second coming of Christ and an obscure theology dedicated to understanding the cryptic Seven Seals (don't ask me!). Allegations of statutory rape and polygamy aside, Koresh's congregation lived relatively peacefully on Mount Carmel, as their compound was known. They bought and sold guns at gun shows and stockpiled inventory — but let's be fair, we are talking about Texas — not only is this a constitutional right, it is a cultural practice.

So the ATF gets wind that the Davidians are modifying AR-15s to make them fully automatic, which some gun experts say isn't so difficult, but is obviously illegal. They push the warrant through; spin a yarn to the army about a crystal meth lab in order to get War on Drugs funding, and tip off the press in order to make a big name for the agency.

Koresh found out about the raid on the morning of February 28, 1993 because the press showed up early. He told the undercover ATF agent (whose identity he knew about but hadn't acted upon) that he knew about the raid. The agent runs over to the rest of the ATF crew who are suiting up and says something to the effect of: the element of surprise is gone, please call the raid off.

At this point it's important to remember that the Davidians are an apocalyptic cult armed to the teeth, waiting for the attack of the armies of "Babylon," whoever they may be.

Nevertheless, the ATF proceeded as planned. No one really knows who fired first, but before the ATF could serve the warrant a gun battle was raging. Ironically, the press had to call ambulances for dead and injured ATF agents because, in their eagerness for operation "Showtime," as it was called, the ATF had failed to remember that small detail.

The FBI took over after the ATF ran out of ammunition (the Davidians didn't), and began negotiations that lasted almost two months. The media was cordoned off and barred from communicating with Koresh and his people (ah, the pre-cellular days). In an effort to drive the Davidians to desperation, the FBI tried sleep deprivation tactics with lights and sound at night. During the day tanks rolled over Davidian cars and, repeatedly, over the grave of one man killed in the initial assault.

"They were trying to take someone that they viewed as unstable to start with, and they were trying to drive him crazy. And then they got mad because he does something that they think is irrational," Jack Zimmerman, an attorney for one of the Davidians, said in a subcommittee.

"I thought the main problem was going to be understanding the psychology of the people inside the compound," Alan Stone a Harvard professor of both Law and Psychiatry, said in the documentary Waco: The Rules of Engagement. "But as I got into it I quickly became aware that the psychology of the people outside the compound was more important."

The negotiations proved futile, not because of Davidian obstinacy, but because the FBI was dead set on ending the siege in a confrontation.

In the end, the FBI used tanks to poke holes in the buildings and fire in CS tear gas. A blaze of disputed origin consumed the compound and everyone inside perished. Conspiracy theories aside, the government's handling of the Waco siege has remained controversial.